Myotonia is a condition present in a number of neuromuscular disorders such as myotonia congenital, paramyotonia congenital and myotonic dystrophy, and is characterized by a delayed relaxation of muscles after voluntary contraction.
Muscular dystrophy is a general term that describes a group of genetic muscular diseases wherein muscles weaken and breakdown over time without involvement of the nervous system. Some of the more common types of muscular dystrophy include:                Duchenne Muscular Dystrophy which is the most common muscular dystrophy that begins in early childhood and is characterized by increasing weakness in the pelvic and shoulder girdles that eventually leads to respiratory and heart failures;        Becker Muscular Dystrophy which is a less severe form of Duchenne Muscular Dystrophy which has a later patient onset and slower progression than Duchenne Muscular Dystrophy;        Emery-Dreifus Muscular Dystrophy which begins early in a patient's life and is characterized by a slowly progressive weakening of the upper arm and pelvic girdle, but the muscles are not hypertrophied;        Facioscapulohumeral Muscular Dystrophy which is a relative benign form wherein the muscles of the face, shoulder girdle, and arm atrophy;        Limb-Girdle Muscular Dystrophy which is a slowly progressive form that may affect either males or females, and is characterized by a weakening or wasting of the pelvic girdle or shoulder girdle;        Myotonic Muscular Dystrophy which is a rare slowly progressive disorder characterized by myotonia followed by atrophy of the muscles including the muscles of the face and neck, cataracts, hypogonadism, frontal balding and cardiac abnormalities; and        Oculopharyngeal Muscular Dystrophy which has an adult onset and is characterized by a weakness of the external ocular and pharyngeal muscles that causes ptosis, ophthalmoplegia and dysphagia.        
There are currently no known cures for muscular dystrophy, however, various drugs have been administered to manage the various symptoms. For example, Foff et al., “Therapeutic Development in Myotonic Dystrophy Type I,” Muscle Nerve, 2011 44(2) 160-169, indicates that drugs such as mexelitine, dehydroepiandrosterone (DHEA) and exogenous insulin-like growth factor (IGF1) have been tried as treatment options without great success. The doctoral dissertation of Amin Haghighat Jahromi, entitled “Advances in Myotonic Dystrophy Type 1 Drug Discovery Through Design of Novel Ligands and Mechanism Establishment,” University of Illinois at Urbana-Champaign 2013, suggests kanamycin, pentamidine, neomycin B, melamine-acridine conjugate N,N′-(propane-1,3-diylbis(azanediyl))bis(propane-3,1-diyl))bis(9-((4-((4,6-diamino-1,3,5-triazin-2-yl)amino)butyl)amino)acridine-4-carboxamide and Hoechst 33528 which has the following structure:
may be useful in treating myotonic dystrophy. The Jahromi dissertation also states that palliative therapy for myotonic dystrophy includes the administration of known compounds such as selenium, vitamin E, baclofen, nifedipine, creatine monohydrate, testosterone, DHEA and bioflavonoids.
It is an object of the present invention to provide methods and compositions that are effective in treating dystrophies such as Duchenne Muscular Dystrophy, Becker Muscular Dystrophy, Emery-Dreifus Muscular Dystrophy, Facioscapulohumeral Muscular Dystrophy, Limb-Girdle Muscular Dystrophy, Myotonic Muscular Dystrophy, or Oculopharyngeal Muscular Dystrophy.
It is a further object of the present invention to provide methods and compositions that are effective in treating myotonia, including myotonia associated with myotonia congenital, paramytonia congenital and myotonic dystrophy.
It is an additional object of the present invention to provide methods and compositions that are effective in treating myotonic dystrophy, including myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2).